A cold front moved across northeast Iowa on the morning of August 15, triggering a line of severe thunderstorms. Law enforcement officials, storm spotters and the public reported wind gusts of up to 65 miles per hour, which knocked down trees and power lines.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS ARX wrote it up.
A cold front moved across northeast Iowa on the morning of August 15, triggering a line of severe thunderstorms. Law enforcement officials, storm spotters and the public reported wind gusts of up to 65 miles per hour, which knocked down trees and power lines.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS La Crosse, WI wrote its last area forecast discussion before the first event at Aug 15, 2:26 AM CST, 3 hours 49 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 326 AM CDT WED AUG 15 2007 .SHORT TERM...TODAY THROUGH FRIDAY NIGHT SURFACE MAP EARLY THIS MORNING SHOWED A RIDGE OF HIGH PRESSURE EXTENDING FROM NORTHERN MN INTO EASTERN WI. MEANWHILE...AN AREA OF LOW PRESSURE WAS LOCATED OVER EASTERN NEB WITH A QUASI-STATIONARY/WARM FRONT EXTENDING EAST THROUGH SOUTHERN IA INTO CENTRAL IL. ISENTROPIC ASCENT OVER THE FRONTAL BOUNDARY COMBINED WITH 850MB CONVERGENCE...AS EVIDENCED BY THE WOODLAKE/SLATER/BLUE RIVER PROFILERS...WAS PRODUCING SCATTERED ELEVATED CONVECTION FROM THE DAKOTAS INTO NORTHERN IA/SOUTHERN MN AND WESTERN SECTIONS OF THE FORECAST AREA. GENERAL ASCENT IN ADVANCE OF A MID LEVEL SHORTWAVE TROUGH EVIDENT ON WATER VAPOR LOOP OVER WESTERN MN WAS ALSO PRODUCING SOME -SHRA ACTIVITY ACROSS NORTHERN WI. 00Z 15AUG07 GFS AND NAM IN GOOD AGREEMENT THROUGH THE PERIOD AS FAR AS THE GENERAL SYNOPTIC SETUP AND FORCING IS CONCERNED. MID LEVEL SHORTWAVE OVER NEB WILL RIPPLE ALONG THE QUASI-STATIONARY FRONTAL BOUNDARY ACROSS IA/IL TODAY. THIS WILL CONTINUE TO PRODUCE ISENTROPIC LIFT/MOISTURE TRANSPORT NORTHWARD ACROSS THE FRONTAL BOUNDARY. WENT WITH CATEGORICAL POPS THIS MORNING BASED ON THIS AND CURRENT TRENDS. TAPERED POPS BACK TO CHANCE CATEGORY THIS AFTERNOON AS IT APPEARS THE BEST LIFT SHIFTS EAST AS THE SHORTWAVE TROUGH DEPARTS. FAIRLY STRONG MID-LEVEL SHORTWAVE TROUGH SWINGING EAST ACROSS CENTRAL CANADA WILL PUSH A COLD FRONT THROUGH THE DAKOTAS INTO EASTERN MN BY LATE THIS AFTERNOON...AND THEN ACROSS WI OVERNIGHT. GFS...WHICH SEEMS TO BE A BIT MORE REASONABLE WITH CAPE GIVEN CLOUD COVER/LOWER TEMPERATURES AND LACK OF GOOD MOISTURE TRANSPORT...PRODUCES CAPE BY LATE THIS AFTERNOON THROUGH THIS EVENING AROUND 1000 J/KG. BELIEVE THIS WILL MINIMIZE SEVERE THREAT WITH THE COLD FRONT DESPITE GOOD AMOUNT OF SHEAR. WILL HAVE TO KEEP A WATCH ON THIS. IF WE CAN GET A BIT MORE HEATING WITH SOME BREAKS IN THE CLOUD COVER LATE THIS AFTERNOON...THEN SEVERE THREAT COULD BE REALIZED PER SPC DAY 1 OUTLOOK GIVEN DECENT WIND SHER AND STEEPEING MID LEVEL LAPSE RATES. A COOLER AND DRIER AIRMASS WILL BUILD INTO THE AREA THURSDAY THROUGH FRIDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE AREA. 850MB TEMPERATURES LOWER FROM 10-15C ON THURSDAY INTO THE 8-12C RANGE ON FRIDAY. LOWS FRIDAY MORNING WILL BE RELATIVELY CHILLY...BOTTOMING OUT IN THE MID 40S TO AROUND 50. HIGHS ON THURSDAY AND FRIDAY WILL BE IN THE 70S. THE HIGH WILL SHIFT EAST OF THE AREA FRIDAY NIGHT WITH LOW PRESSURE ORGANIZING OVER THE NORTHERN PLAINS. THIS WILL LIFT A WARM FRONT BACK NORTH INTO WESTERN MN/IA. STRONG ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THE LOW AND WARM FRONT WILL LIKELY PRODUCE AN MCS SOMEWHERE NORTHEAST OF THE FRONTAL BOUNDARY. THIS ACTIVITY COULD SPREAD EASTWARD INTO THE AREA LATER IN THE NIGHT. TRENDED POP/WX GRIDS TO REFLECT THIS. .LONG TERM...SATURDAY THROUGH TUESDAY 00Z 15AUG07 GFS AND ECMWF IN FAIRLY GOOD AGREEMENT THROUGH THE PERIOD. BOTH SHOWING A VIGOROUS MID LEVEL TROUGH MOVING EAST FROM THE PACIFIC NW INTO THE NORTHERN PLAINS THROUGH THE PERIOD. THIS WILL DEVELOP SURFACE CYCLOGENESIS ACROSS THE NORTHERN PLAINS WITH LIFT ACROSS A QUASI-STATIONARY FRONTAL BOUNDARY IN PLACE ACROSS THE CENTRAL PLAINS INTO IA/IL. THIS WILL LEAVE THE FORECAST AREA SUSCEPTIBLE TO MCS ACTIVITY THROUGH MONDAY. IT APPEARS THE LOW WILL LIFT NORTHEAST INTO CANADA...SWINGING A COLD FRONT INTO THE AREA ON TUESDAY FOR A CONTINUED CHANCE OF SHRA/TS. CURRENT GRIDS ALREADY HAVE SHRA/TS CHANCES...SO NO CHANGES MADE. && .AVIATION... MOISTURE TRANSPORT AND ISENTROPIC UPGLIDE OVER THE FRONTAL BOUNDARY TO THE SOUTH WILL KEEP THE POSSIBILITY FOR SHOWERS AND EMBEDDED THUNDERSTORMS NEAR AND SOUTH OF THE TAF SITES THROUGH THE MORNING AND INTO EARLY AFTERNOON. ACTIVITY IS HIGH BASED...AND COMBINED WITH LIGHT WINDS...WILL CONTINUE TO SEE AREAS OF LIGHT FOG/MIST WITH PATCHY MVFR VISIBILITIES AND ISOLATED POCKETS OF IFR/LIFR WHERE FOG AND STRATUS GET THICKEST. MEANWHILE...THE NEXT UPPER LEVEL SHORT WAVE TRACKING ACROSS SOUTHERN CANADA...AND ASSOCIATED SURFACE COLD FRONT...WILL HEAD INTO THE REGION TONIGHT. LOOKING LIKE THE BEST CHANCE FOR ACTIVITY FOR THE TAF LOCATIONS WILL OCCUR DURING THE OVERNIGHT HOURS...SO WILL BE PONDERING THIS FOR THE 12Z TAF ISSUANCE. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && SHORT AND LONG TERM - DAS AVIATION - MW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 525 AM CDT WED AUG 15 2007 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034- 041>044-053>055-061-161100- ADAMS-ALLAMAKEE-BUFFALO-CHICKASAW-CLARK-CLAYTON-CRAWFORD-DODGE- FAYETTE-FILLMORE-FLOYD-GRANT-HOUSTON-HOWARD-JACKSON-JUNEAU-LA CROSSE- MITCHELL-MONROE-MOWER-OLMSTED-RICHLAND-TAYLOR-TREMPEALEAU-VERNON- WABASHA-WINNESHIEK-WINONA- 525 AM CDT WED AUG 15 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF NORTHEAST IOWA... SOUTHEAST MINNESOTA AND SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...TODAY AND TONIGHT WARM AND MOIST AIR...RIDING UP AND OVER A FRONTAL BOUNDARY ACROSS IOWA....WILL GENERATE SHOWERS AND THUNDERSTORMS FOR THE OUTLOOK AREA TODAY...PARTICULARLY THIS MORNING. A FEW STORMS MAY PRODUCE GUSTY WINDS AND SMALL HAIL...BUT WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED. HEAVY RAINFALL IS A POSSIBILITY HOWEVER...WITH RAIN AMOUNTS BETWEEN 1 AND 3 INCHES. LATER TODAY...A COLD FRONT WILL APPROACH FROM THE WEST...ALONG WITH AN UPPER LEVEL DISTURBANCE. THESE MAY FUEL NEW THUNDERSTORMS BY TONIGHT. ONCE AGAIN...WIDESPREAD SEVERE WEATHER IS NOT EXPECTED...BUT A FEW STORMS MAY PRODUCE HAIL AND GUSTY WINDS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SEVERAL WEATHER DISTURBANCES ARE EXPECTED TO CROSS THE REGION FROM FRIDAY NIGHT RIGHT ON THROUGH NEXT TUESDAY. WITH EACH DISTURBANCE THERE WILL BE A THREAT FOR THUNDERSTORMS. IT REMAINS TOO EARLY TO TIME THE ARRIVAL OF STORMS...AND HENCE THE POSSIBILITY FOR SEVERE WEATHER. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED...BUT REPORTS OF RAINFALL WOULD BE APPRECIATED TODAY. .EMERGENCY MANAGEMENT COORDINATION... NO CALL IS SCHEDULED. MW
The Des Moines radar (KDMX), 158 km away, was scanning. The volume nearest the first event began at 12:14 UTC.
4 thunderstorm wind. Local standard time, as filed.
Trained spotter reports several 12 inch diameter trees and limbs down.
Trained spotter reports several trees down and some barns blown over. All the damage was near and south of Nashua.
Power outages were reported by the post office.
The cooperative weather observer reported several power lines down on the south side of Oelwein and a marquee sign at Oelwein vet clinic blown down.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2007Every state in 2007This day in weather historyWarnings in Iowa, August 2007
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 45028, 45031, 45033, 45037.